One of the serious challenges the semiconductor industry faces is developing new gate dielectric materials for DRAM and capacitors. For decades, silicon dioxide (SiO2) was a reliable dielectric, but as transistors have continued to shrink and the technology has moved from “Full Si” transistors to “Metal Gate/High-k” transistors, the reliability of the SiO2-based gate dielectric is reaching its physical limits. The need for new high dielectric constant materials and processes is increasing and becoming more and more critical as the size for current technology shrinks.
US Pat App Pub No 2005/277223 discloses ALD methods of forming metal oxides using metal-containing precursors having the formula M(L1)x(L2)y, wherein M is a metal, L1 and L2 may be halide, diketonate, alkoxide, amino, alkoxyamine, amidinate, or multidentate ligands. The exemplary precursors however are only Hf(OtBu)2(NEtMe)2, Hf(OtBu)2(NEt2)2, Hf(NEt2)2(DMAMP)2, Hf(NEtMe)2(DMAMP)2, Ti(OtBu)3Cl, Ti(OtBu)3Me, Ti(OtBu)2(NEt2)2, Ti(NEt2)2(DMAMP)2, Ti(OtBu)2(DMAMP)2, and TiCl2(DMAMP)2.
U.S. Pat. No. 7,491,654 discloses ALD methods of forming ZrO2 thin films using a tris(N-ethyl-N-methylamino)(tertbutoxy)zirconium precursor.
Other sources and methods of incorporating Hf-containing and Zr-containing materials are being sought for new generations of integrated circuit devices. Novel precursors are needed.